The Varying Characterization of Alkali Metals (Na, K) from Coal during the Initial Stage of Coal Combustion

The first step in controlling alkali gaseous phase concentrations in flue gas is understanding their behavior during coal combustion. The behavior of sodium and potassium in coal during the initial stage of combustion was investigated. A series of tests were conducted under two combustion temperatures (800 °C and 900 °C) and two atmospheres (21 vol % and 6.36 vol % O2). The data indicated that only a small portion of alkali metal in the coal was released during the initial stage of combustion process (e.g., devolatilization and volatile combustion stage). The varying behaviors of different occurrence modes of alkali metals were also studied, that are identified by sequential extraction with the solutions of water, 1 M ammonium acetate, and 1 M hydrochloric acid, respectively. In general, the water-soluble (WS) alkalies in the burning residue decreased with an increase in exposure time on high temperature combustion atmosphere, while the hydrochloric acid-soluble alkalies showed an opposite tendency. This ...

[1]  P. Agarwal,et al.  The role of inorganic matter in coal in the formation of agglomerates in circulating fluid bed combustors , 1993 .

[2]  P. Agarwal,et al.  The fate of organically bound inorganic elements and sodium chloride during fluidized bed combustion of high sodium, high sulphur low rank coals , 1992 .

[3]  O. Howarth,et al.  Solid-state nuclear magnetic resonance studies of sodium and aluminium in coal , 1987 .

[4]  R. Greegor,et al.  Investigation of the structural forms of potassium in coke by electron microscopy and X-ray absorption spectroscopy , 1986 .

[5]  D. H. Maylotte,et al.  Forms of potassium in coal and its combustion products , 1986 .

[6]  W. Pearce,et al.  The mode of occurrence and combustion characteristics of chlorine in British coal , 1986 .

[7]  A. Sarofim,et al.  The fate of sodium during pulverized coal combustion , 1985 .

[8]  Steven A. Benson,et al.  Comparison of inorganic constituents in three low-rank coals , 1985 .

[9]  E. Raask,et al.  External corrosion in coal-fired boilers: Assessment from laboratory data , 1981 .

[10]  Walter R. May,et al.  High-Temperature Corrosion in Gas Turbine and Steam Boilers by Fuel Impurities—Part VI: A Statistical Study of the Effects of Sodium, Temperature and Additive on Corrosion Rate and Slag Friability , 1976 .

[11]  J. B. Murray.  Changes in state of combination of inorganic constituents during carbonization of Victorian brown coal , 1973 .

[12]  H. Gluskoter,et al.  Chlorine and sodium in Illinois coals as determined by neutron activation analyses , 1971 .